According to the TiVo schedule it looks as though the guests are repeat segments this week - interviews from previous visits to the R&K studios. Not sure when Neil's is from, though probably pre-Dr Horrible (it's listed as him coming to talk about HIMYM), but still should be new to a lot of people here!

He's just an actual guest this time, from what I can tell - the four guests are all listed as "repeat segment" and Regis and Kelly have (usually, when that happens) pre-recorded their host chat sections to link the repeat guest segments together.